transposition_cipher_test.py

# Transposition Cipher Test

import random
import sys
from transposition_encryption import encrypt_message
from transposition_decryption import decrypt_message


def main():
    random.seed(42)  # set the random "seed" to a static value
    for i in range(20):  # run 20 tests
        # Generate random messages to test.
        # The message will have a random length:
        message = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' * random.randint(4, 40)
        # Convert the message string to a list to shuffle it.
        message = list(message)
        random.shuffle(message)
        message = ''.join(message)  # convert list to string
        print('Test #%s: "%s..."' % (i + 1, message[:50]))
        # Check all possible keys for each message.

        for key in range(1, len(message)):
            encrypted = encrypt_message(key, message)
            decrypted = decrypt_message(key, encrypted)
            # If the decryption doesn't match the original message, display
            # an error message and quit.
            if message != decrypted:
                print('Mismatch with key %s and message %s.' % (key, message))
                print(decrypted)
                sys.exit()
        print('Transposition cipher test passed.')


# the main() function.
if __name__ == '__main__':
    main()